Field of the Disclosure
The present disclosure relates to an interference checking device which checks whether interference occurs between components, such as a structure of a numerically controlled machine tool (NC machine tool), a tool and a workpiece.
Background of the Disclosure
On an NC machine tool, the operations of its drive mechanisms (e.g., a feed mechanism, a spindle motor, etc.) are usually controlled by a numerical controller in accordance with a previously generated machining program.
Conventionally, when operating such a drive mechanism in accordance with the machining program, it is checked whether the movement of a movable structure (e.g., a tool rest, a saddle, a table, a spindle head, etc.) driven by the drive mechanism causes interference between structures (including fixed structures and movable structures) which are components of the machine tool, a tool and a workpiece. This check is performed because, if the machining program includes an error, there is a risk that, when the drive mechanism is operated in accordance with the machining program, interference occurs between the structures, the tool and the workpiece, thereby inflicting serious damage on the structures, the tool or the workpiece.
Conventional examples of apparatus for performing such an interference check are provided in Japanese Unexamined Patent Application Publication Nos. H10-55209 (“JP '209”) and 2009-54043 (“JP '043”).
The numerical controller disclosed in JP '209 has tool-interference-check processing means performing a tool interference check on a machining program, and tool-interference-check-necessity determining means determining the necessity of the tool interference check. The tool-interference-check-necessity determining means is configured to compare the date of execution of the tool interference check with the date of change of tool-related data settings and thereby, if the tool interference check is not executed after a change of the tool-related data settings, determine that the tool interference check is necessary, and the too-interference-check processing means is configured to, based on the result of the determination of the tool-interference-check necessity determining means, execute the tool interference check only when the tool interference check is necessary.
According to the numerical controller of JP '209, since the tool interference check is executed after a change of the tool-related data settings, that is, only when the tool interference check is necessary, an effect of avoiding unnecessary repetition of the tool interference check and improving the processing speed of the numerical controller is obtained.
Further, the numerical controller disclosed in JP '043 has a function of defining an interference area for each of a plurality of machine structures, moving the interference areas based on machine coordinate values of the machine structures which are updated by interpolation processing, and checking whether the interference areas for the machine structures interfere with each other. This numerical controller has automatic interference-check-calculation-cycle adjustment means for automatically adjusting a cycle of interference check calculation by dividing an operation time required for interference check processing by a time occupied by the interference check processing in one interpolation processing cycle, interference-area expanding means for expanding the interference areas based on the maximum feed speed of each axis and the cycle of interference check calculation, and means for checking whether the expanded interference areas interfere with each other.
According to the numerical controller of JP '043, since the cycle of interference check calculation is automatically adjusted, even if the amount of the interference check is increased, the interference check calculation can surely be completed without affecting the interpolation processing by the numerical controller.